This invention relates to feeding sheets in a printing machine, and more particularly to an improved paper transport for sheets fed from a top vacuum corrugation feeder in such a machine.
High volume, high speed printing machines produce copies at a rate in excess of several thousand copies per hour, therefore the need for a sheet feeder to feed cut copy sheets to the machines in a rapid dependable manner has been recognized to enable full utilization of the machines' potential copy output. These sheet feeders must operate flawlessly to virtually eliminate the risk of damaging the sheets. Current top and bottom vacuum corrugation feeders are solutions to this high speed, high volume sheet feeding requirement, however, these feeders depend upon the principle of top or bottom sheet corrugation for sheet separation from a stack of sheets in a feed supply tray and as a result, a new problem has surfaced when transporting such a sheet through a conventional designed multi-roll transport system. The sheets are delivered corrugated to the transport system and the corrugation remains in the sheets and creates problems when transport around curves is required as well as copy quality and jam problems.
Accordingly, a solution is a decorrugating device consisting of a drive shaft with three drive rollers and an idler shaft with three complimentary idler rollers. The drive rollers are not completely cylindrical, but shaped so that the two identical sets of outer drive and idler rollers form driving nips during part of the rotation of the drive shaft. During this period corrugation spreads outwardly from the center. The center roller set then takes over the driving and the outer nips open allowing the corrugation to dissipate.